This invention relates generally to non-aerosol, foam dispensing devices and particularly to a foam dispensing device which is used in the inverted position.
Foam dispensing devices of the type under consideration have been known for at least fifteen years and are represented by U.S. Pat. Nos. 3,422,993 issued to G. L. Boehm; 3,709,437 issued to H. E. Wright; 3,622,049 issued to R. E. Thompson and 4,024,992 issued to Schmid. Of these patents the Boehm and Wright disclosures are believed most pertinent and show devices that can be used in the inverted condition. Boehm makes no specefic provision for air return and Wright provides a valved air return system in the foam discharge conduit. The Thompson patent discloses a separate air return system but cannot be used in the inverted position. One other known foam dispensing device manufactured by Ballard Medical, Inc., the assignee of the present invention provides a separate air return conduit which extends into the container air space when the container is inverted. However, the foam producing means is under liquid head during operation which leads to undesirable migration of unfoamed liquid through the spout when the device is inverted.
The present invention solves the above described problems in a manner not disclosed in the known prior art.